The hair colors were made lighter to allow for whiter hair, as stated in the patch notes for Season 9 on April 22, 2014.
It is now possible to get much whiter hair for most hairdos but is limited by species color options.
In a recent
Tribble thread, crypticjoejing said that there would be another hair color update, because someone pointed out that black hair wasn't really black anymore. I don't know if this update has made to Holodeck yet. For blonde and brown hair, I don't see much difference between the screenshots I took on Tribble before Season 9 and those I took on Holodeck after Season 9.
Below are screenshots I took on Holodeck before and after Season 9. Certain hair colors, particularly blonde and brown, look noticeably lighter. Also, the hair seems shinier than before. I don't know whether the increased shininess is deliberate or a side effect of the
lighting differences I'm seeing throughout the game. Note that I have not changed the setting on the "Shininess" slider.
Human female (blonde hair)
Before Season 9,
After Season 9
Human female (brown hair)
Before Season 9,
After Season 9
(Also note that the hairline on female hairstyle "Ponytail 04" has receded, making the bangs look misplaced.)
Vulcan female (red hair)
Before Season 9,
After Season 9
Alien female (purple hair)
Before Season 9,
After Season 9
Human male (brown hair)
Before Season 9,
After Season 9
Waiting for a programmer ...
Comments
You can notice the costume in the screenshots being brighter as well as the hair.
STO Screenshot Archive
Please note that there are two separate issues. The hair colors were made lighter; this has been acknowledged by Cryptic. The lighting issues are another matter, though they may have an effect on the appearance of hair.